On 4 Gen, 11:51, Andreas Tekman wrote:
On 1 Jan., 17:09, giannibo wrote:
On 31 Dic 2007, 23:35, Jim Yanik wrote:
giannibo wrote :
On 29 Dic, 04:43, Jim Yanik wrote:
"DaveM" wrote
innews:gcOdnekazMCkC-janZ2dnUVZ_
:
"David Wright" wrote in message
...
If you get some money send it in for repair and calibration. *Cost
on
good test equipment is out of site.
"giannibo" wrote in message
om
...
HELP! Someone know the mainframe oscilloscopeTektronix7000
series? I have some 7704 with power supply broken,with same
defect: don't start the oscillator.
Some suggestion??
You can download the manual for the 7704 from
http://bama.edebris.com/manuals/tek/7704/. *It should help you
figure
out the problem.
The usual suspects are aging electrolytic capacitors.
both in the power supply and the mainframe itself.
just make sure you have a 7704 and not a 7704A. There's a big
difference.
although both have complex series-resonant switching power supplies..
usually,you hear a clicking or "chirping" from the PS;it's trying to
start,but something is loading a supply,or a diode is shorted.
Some failures blow a lot of parts....and then the line fuse
afterwards.
--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -
- Mostra testo tra virgolette -
Thanks for answer.The model is 7704A. I replace the fast diode.The
defect remaining is that try to start the oscillator,but isn't
stable.After several test, I *found that disconnecting the transistor
TO5 on parallel to base-emitter of power transistor, the oscillator
start, but isn't stabilized.May be is the small SCR. I checked all
components, only the SCR remain... Further the semiconductor indicated
on circuit as a element with 2 emitter, what is?
A Diac;it triggers at ~33V IIRC.
This machine remain on
stock for several years, so some components are gone.Is a pity ,
because this instrument is made on beautifull mode, and I try to save.
Thanking for help!!
Gianni
--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -
- Mostra testo tra virgolette -
Thanks! I will replace it! In the meantime I foun that R120 and *R122
( 1,8 Kohm) *of Z axis board A41 are burning, with smoke. Many defect
all togheter!! Tomorrow i will check why these resistor are
smoking.Anyway I am bidding on *ebay a 7704 so I can compare some
situations.
Thanks. I wil post when I found all defect!
Gianni
IK4EWH- Zitierten Text ausblenden -
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Remember what Jim already said about 7704 and 7704A: Both models are a
lot different.
So if you plan to compare circuits and repair faults, go for the same
models at least.
hth,
Andreas- Nascondi testo tra virgolette -
- Mostra testo tra virgolette -
The model is 7704A and I got diagram. Now is working but isn't active
the automatic control. I must replace the DIAC. But rhey are others
defects... very hard competition!